Patent EP-A-1690454 describes a tenderizing machine applicable to the treatment of pieces of boned meat comprising two superposed tenderizing assemblies, each of which comprises a pair of parallel tenderizing rollers having a plurality of cutting members such as prongs or blades emerging from their surfaces. The tenderizing rollers of each pair are rotatably assembled close to one another, defining between them an opening with adjustable width. One of the tenderizing rollers of each assembly is supported with the possibility of moving away from the other one, acting against antagonist means during the passage of the pieces of meat between both tenderizing rollers. The machine includes, for each of said tenderizing assemblies, means for individually regulating the distance between the two tenderizing rollers and means for selectively locking the position of the tenderizing roller capable of movement.
A single electric motor is operatively connected by means of a mechanical transmission to rotate the two tenderizing rollers of each pair in opposite directions, and said mechanical transmission is configured such that the rotational speeds of the two tenderizing rollers of each pair are unequal. By means of this construction, the ratio of rotational speeds of the two tenderizing rollers of each pair remains constant even though the rotational speed of the motor varies, unless the elements of the mechanical transmission are modified, and this is able to be improved since for different types of meat or for different treatments it may be convenient to vary the ratio of speeds between the two tenderizing rollers.